weaning foods and the use of contaminated water are often implicated in
weaning diarrhoea and it has been estimated that 15 – 70% of all diar-
rhoea episodes in young children are food associated.
6.3 Incidence of Foodborne Illness
Statistics covering foodborne illnesses are notoriously unreliable. Simply
quantifying the problem of those diseases initiated by infection through
the gastrointestinal tract is difficult enough, but to determine in what
proportion food acted as the vehicle is harder still.
Many countries have no system for collecting and reporting data on
gastrointestinal infections and even where these exist the reported data is
acknowledged to represent only a fraction of the true number of cases.
Studies have suggested that the ratio of actual to reported cases can be
between 25:1 and 100:1. One should also be circumspect about using
published national statistics for comparative purposes since apparent
differences can often simply reflect differences in the efficiency of the
reporting system. In the United States, reporting of foodborne illness
outbreaks to the Center for Infectious Diseases, is not compulsory so
that some States report rates 200 times those of other States. In the early
1980s reported outbreaks of foodborne disease for the United States
were roughly twice those reported by Canada which has a population
only one tenth the size. It seems unlikely that Canadians are markedly
more susceptible to foodborne illness or more careless about food
hygiene than their neighbours; more probably the disparity reflects a
higher level of under-reporting in the United States. Some support for
this appears if the statistics for all gastrointestinal disease are compared.
These are a much closer reflection of the relative population sizes since
these figures are officially notiable in the USA.
Such statistical problems are not unique to North America. The WHO
Surveillance Programme for Control of Foodborne Infections and In-
toxications in Europe which reports data from more than 30 countries
has noted the different national systems of notification and reporting.
These include:
(i) notification of cases of foodbornedisease without any specification
of the causative agent or other epidemiologically important details;
(ii) reporting only laboratory-confirmed cases of foodborne disease
collated by a central agency;
(iii) reporting cases of gastrointestinal infection which, in some cases,
are regarded as being foodborne regardless of whether the
involvement of food has been established;
(iv) reporting only cases of salmonellosis.Chapter 6 165